1. Field of the Invention
Embodiments of the present invention generally relate to screws used to secure components in a hard disk drive, and more specifically to lubricating the screws.
2. Description of the Related Art
Nearly every kind of computer today, be it a desktop computer, server, mainframe or supercomputer contains at least one hard disk drive (HDD). In fact, even some modern electronic devices such as camcorders and VCR's incorporate hard disk drives. The advantage of including hard disk drives is that they can store large amounts of information including the programs and data required to operate and use computers and electronic devices.
A hard disk drive comprises several mechanical components such as magnetic disks, actuator arms and electromagnetic heads to read/write data. A magnetic disk may contain concentric data tracks containing the data stored on the disks. The actuator arm may be coupled with an electromagnetic head. The electromagnetic head may be placed on a track of an associated disk to perform read and write operations. In addition to the disks and actuator arms, a hard disk drive may also contain motors for rotating the magnetic disks and moving the actuator arms to place a head at a particular location on a disk.
The components of a hard disk drive may be secured in a chassis using a combination of clamps and screws. However, installing screws may be difficult because of the high friction between the screw threads and mating parts in a bore during fastening. Due to the high friction, different screws may be fastened differently causing different clamping loads on the screws. Therefore, mechanical components may not be properly aligned. Additionally, due to the variations in clamping loads the components may be susceptible to shifting and misalignment upon the application of even minor shock to the hard disk drive. Furthermore, the screw fastening process may generate metallic particles that may deposit on sensitive portions of magnetic disks, thereby affecting the performance of the disks.
Screws used to secure components of a hard disk drive may be coated with a lubricant to lower the friction during screw fastening. For example, currently, P104 a surfactant available under the trademark PLURONIC from BASF corporation, a difunctional block copolymer surfactant terminating in primary hydroxyl groups, is used to coat screws used in HDD's. Screws coated with P104 offer several advantages over non-lubricated screws such as higher clamping load with narrower force variation and less metallic particle generation during fastening.
However, using P104 as a lubricant has several disadvantages. For instance, P104 has a relatively low melting temperature of around 32° C. Therefore, P104 may change phase to a liquid even at room temperature. Liquid P104 may migrate to other parts of the HDD such as the magnetic disk surface, thereby contaminating the surface. P104 also has a relatively low decomposition temperature of around 150° C. with a ramping rate of 20° C./min from room temperature. Decomposition of P104 may generate acids which may further damage the magnetic disks. The low decomposition temperature of P104 also results in a low shelf life of only about 2 years.
Furthermore, P104 has rather high water solubility. Therefore, P104 materials deposited on screws and elsewhere in the HDD may soak up moisture and cause disk drive components to rust over time.
Therefore, what is needed are better methods and materials for lubricating HDD screws.